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3-D-printed plastic objects can track their own use without any electronics
来源于:MIT Technology
We propose a formula for the enumeration of closed lattice random walks of
length $n$ enclosing a given algebraic area. The information is contained in
the Kreft coefficients which encode, in the commensurate case, the Hofstadter
secular equation for a quantum particle hopping on a lattice coupled to a
perpendicular magnetic field. The algebraic area enumeration is possible
because it is split in $2^{n/2-1}$ pieces, each tractable in terms of explicit
combinatorial expressions. 查看全文>>